Projector slide film changer



Oct. 13, 1953 R. A.. L IGHTBURN ET AL PROJECTOR SLIDE FILM CHANGER 2 Sheets-Sheet l Filed Jan. 2, 1951 A (lull.

Oct. 13, 1953 R. A. LIGHTBURNI ET AL 2,655,075

PROJECTOR SLIDE FILM CHANGER Filed Jan. 2, 1951 2 Sheets-Sheet 2 mi 'Tiil ATTORNEY Patented Oct. 13, 1953 UNITED STATES PATENT OFFICE '2,655,075 IROJ()T011.' SLIDE CHANGER Robert AzHLigh-tburn, Fayson Lakes, vN. J., and` `Mervyn W. Palmer, New York, N. Y., assigno'rs fo American Optical Company, Southbridge, Mass., a' voluntary association of Massachusetts Application Januaty, 1951, Serial- No ,203,904t 11 Claims. (ci. ss-zs'i The present invention `relates-toa slideilm changing attachment for a: projector of! the type in which a lm carryingsuccessive frames .or slides is movable step by step by aieedasprocket wheel to bring, the successive. frameszinto`r azprojection position. The present invention@relates particularly to an. attachment for'suchiaprojector having means by which4 .the intermittent movement. of. afeedsprocket for: frame changing may be manually controlled to move: the feed sprocket one step whenlva` change: desiredand to move. thereby' the next frameon. the: slide nlm into projecting position. This attachment includes a Genevadevice for moving: the slide nlm through: an amount equalitoone frame Itis importa-nt that thestar Awheel of theG'eneva device be rotated exactly: one stepof predetermined extent, whena frame cnangeiisindicated, so that the next view is;broughtint'o'A exact'reg'i'stry for projection on the screen andthatthisV wheelv be locked inthe intervals between view changing operations. Otherwise; the Geneva star wheel may be accidentally displaced during-thesezintervals causingY the f viewf being projected to; bei displaced out-of screerrreglst'rylv and bringing thereby the star Wheel out of proper rotative-relationship With respect to'- a pinA carrying' drive-wheel of the Geneva device;

The ordinary Geneva device" has-a-` locking disc rotatable with thepin carryingY driveI wheel and having its circular periphery-'movable into 'conforming contact with the circularly concave peripheral conformations or' they Geneva star wheel between its points: lockingdi's'cy has a segmental cut-out movablel opposite the-star wheel in position vtov releasesaid vstarwheel for rotation when slide fllm changegis'# indicated: This locking ldisc is not'always effect-ivev during the transitional periods attlebeginningfandlend' of-'each cycle of rotation of the Geneva star wheel;

@ne object ofthe present' invention; isi-tc` pro'- vide a new and improvediframefchanglng attach:- ment for a slide'lmprojectorflavingfmeansfby which movement offthefframeslidessuccessively throughmanual controlinto properfprojection position is assured and 'theL maint'ena-nce of v the selected frames or slidesf ini this pofsltionfduring the periods between-"slide lmfchangingv4 controll manipulations is made cer-tain` y A further obj ect isl to provide-a-iiaine changing attachment for aslide lm' projector havingf a Geneva movementiwith new `and improved means for assuring` the locking' offits 4star wheel in xei position duringc thea periods between; frame changing-.operations.

Another object is to, provide new and improved switch! means for manually controlling the operation of the/slide lm changer.

Another object is toprovide a frame changing device .having braking means associated therewith to assure against the overrun of certain of its-rotative partsbeyond proper stopping position at the end-of each frame changing operation.

Alstill further object is to ,provide a slide lm changingr device in the form ofl a compact selfcontained unitwhich can be attachedV to or removedf fromv a projector asxsuch, and'which lends itself to positional adjustmentwitn respect to the projector according to=thef type, elevation or inclination of thesprojecto'r.

Variousother objects of theinvention arel apparlent from the following particular description andfromJ an inspection .of the accompanying drawings, iniwhich- Figure': 1 is a top'plan view of a projector showing. da'grammatically the slide lmv changer of the present.'invention. attached? thereto;

Figurelv2 is a fragmentaryl sideelevationv of the lprojectorshowingfdiagrammatically the slide film changerattached thereto;.

Figure-fisa sideview of,r the slide'film changer embodyingfthe 1presentinvention and shown'with thecoverlofit's'fca'sing removed or broken away and duringfth'e' periodwhenlthe lmfeedsprocket islb'eing-j rotated Y to bring' the next frame slide on th'e illmliiitoproj ecticnlview';

v'Figure 4i's asec'tion oftheI slide film changer taken app'roi'rirn'ately alon'gl the lines 4-4 of Fig; 31;

Figurey 5 is" an endf view* oftheI slide nlm changer;

Figure 6 isia sideview of? theioperating mechanisn o'ff the changer! showny during normal inactiveiperiods when a-4 frameI or slide is in projectionv'iew AFigure" 7 isa'sldeiview offtlieoperating mechanisin". off the changer shown after the changing ff frames onf-the`1slide-1fllm has been manually initiateianii while one frameor slide'ismoving outvof projection View and the next frame or slide isiv movingi into; proj ect'i'onf view;

Figure islalfragmentary side-view'of-the operating of the changer-shownright after; thesnext frame kor slide'v has= ccmpleted its movement Y into projection view 'Figure 9isa sideiview of' the' switch for manually controlling' thelo'peratingi of the slidefllm changer; and

Figure i l0` is a frontlvlewV ofi the switch.

iilm carries in its successive frames the ldifferent views or slides.

The slide i'llm changer I 8 is adapted to be supported in proper position with respect to the projector II and to be removably secured to the feed sprocket shaft I5. This slide film changer I has a casing I1 to which a leg I8 telescopically constructed for lengthwise adjustment is removably secured as for example, by screwing into the bottom of the casing. The lower endof this leg I8 has a wheel 20 adaptedto -be supported on the projector base I2 in mounted attached position of the slide iilm changer I0. Between its point of attachment tothe feed sprocket shaft I5 and the leg I8, the slide film changer I0 is stably supported and may be tilted about the axis ofthe feed sprocket shaft I5 to accommodate said slide changer to different types of projectors and to diiferent elevations or inclinations of the projector with respect toits base I2.

The slide film changer I0 shown in Figs. 3 to 8 includes the frame casing I'I having a rear wall 25 with an opening 26 to permit certain parts of the `operating mechanism 'of the changer to project therethrough and corners 21, 28, 30 and 3l provided with tapped holes 32 for removably attaching a cover plate 33 to said casing. Secured to the rear wall 25 is a frame plate 34 to` which is fastened a motor 35 having coils 33, an armature 31 and a shaft'38. This motor shaft 38 carries a roll 40 in continuous friction drive engagement with a wheel 4I shown comprising a disc 42 of elastomeric material such as rubber held between twometal discs 43 and having its periphery in driven engagement with the friction roll 43. The wheel 4I has a oating mount and for that purpose is supported on one end of a link l45, the other end being connected to an arm 46 on a fixed pivot support 41. The mounting for the friction wheel 4I on the link 45 is shown comprising an axle pin 48 rigidly secured to the link 45 as for example by riveting and supporting the friction wheel for free rotation thereabout. The friction wheel 4I maybe provided with a suitable bushing (not shown) for bearing embracement of the axle pin 48. The pivot connection between the arm r46 and the link 45 is shown comprising a pivot pin 53 rigidly secured to the link 45 as for example by riveting and rotatively embraced by one end of said arm; The fixed pivot support 41 for the other end o-f thearm 46 is shown'in the form ofa pinV affixed to theA motor frame Vplate 34, as'for example by riveting and rotatively embraced by said arm; Y i

A spring 55 has one endsecured to the link 45 at V56 andthe other end anchored in fixed position at 5l to the motor frame plate 34 and serves to urge the friction wheel 4I in peripheral friction drive engagement with an veccentric wheel 58 mounted'for rotation on a shaft 60 j'ournalled in a xedbearing 3l vforming part wheel 63 formed with radial slots 64 at each point `and adapted to be turned step by step by a tooth or pin 35 on said eccentric wheel moving into said slots. This star wheel 53 is removably secured to a shaft 65 by means of a collar 5l and a clamping nut 68. A coupling sleeve 'I8 rigid with the star wheel shaft 36 is journalled in a fixed bearing 'II forming part of the rear casing wall 25 and projects beyond said bearing to permit the shaft I5 of the feed sprocket I4 to be inserted therein. A set screw I2 in the coupling sleeve 'I8 serves to lock the two shafts I5 and 55 for rotation in unison.

`VThe rotationv of the star wheel shaft 55 and in turn the feed sprocket shaft I5 is controlled remotely byan operator or lecturer by manipulating a switch 8| V(Figs. 9 and 10'). Toward that end, there is provided an electromagnet I5 supported in* the Acasing Il and consisting of a coil 'Il and a pole 13. Connected to the arm 45 is an armature 30 adapted to be attracted by the magnet pole 18. YThe electromagnet 'i5 as well as the motor 35 are connected in parallel to a source of current through a conductor 'I9 passing through one of the casing corners 21 and adapted to be plugged into a wall outlet (not shown). The circuit of the magnet coil 'II is controlled by the switch 8| connected to the end Vof a long conductor cord 482 insaid coil circuit also passing through acasing wall.

The motor 35 is continuously operating and the magnet l5 4is ordinarily continuously magnetized, so that the armature is normally in contact with the magnet pole i8. The wheel 4I will thereby be drawn by the linkage 45, 45 against the action of the spring 55 about the motor roll 4t as a center andawayfrom drive co-ntact with the eccentric wheel 58 of the YGeneva movement, and thus into the inactive or nondriving position shown in Fig. 6. Under these conditions, even though themotor 35 is operating and the wheel 4I in contact therewith is rotating, the drive to the Geneva movement is interrupted and the Geneva star wheel 53 connected to the feed sprocket I5 will be stationary. In this position of the slide lm changer, a frame or slide on the lm will register with the objective of the projector and the view of said frame will be projected in fixed position on the screen. When the operator orV lecturer desires to change the view, he operates the switch 8i to open the circuit of the magnet l5. This action momentarily deenergizes the magnet 'I5 and releases the armature 80. This action causes the rotating wheel 4I to be released f'or movement into drive engagement with the eccentric wheel 58 of the Geneva movement by the action of the spring 55; into the position shown in Figli.l AThe eccentric wheel 58 thereafter continues its rotation into position shown in Fig. 7 and then into position shown in Fig. 8. `This causes the Geneva star wheel 63 to be rotated onestep of 90 and the :film to be moved thereby one step to bring the next frame Vinto projecting register. In the position shown in Fig.' 8*, the Geneva star wheel 63 has terminated its 4one step movement but the eccentridwheel 58 continues `its movement towards the inactive position shown in Fig. 6.

The switch 8i after it is manipulated into circuit opening'positionjto deenergize the magnet i5 and thereby to-initiate operation of the Geneva movement is returned fintoY circuit closing Vposition even before'the Geneva movement has completed its one step operation:V vThe ecoentric'wheel 58, after the Geneva star wheelyg831 has stopped and while it is in the rotative position shown in Fig. 6, will yhave its side 'of maximum throw the wheel 4| will be out of drive 4contact 'with the eccentric wheel'58 as a result of" the attraction of the magnet pole 18 fo'rthe armature 88.

rAfter the switch 8| has been 'opened vrand the wheel'4 |'has been released into drive engagement with the'eocentric wheel v58, the rotation of said 'eccentric wheel counterclockwise (Fig. 6) will move the/side 'of maximum throw of the eccentric wheel away from the wheelllyso that ysaid jwheel 4| will bemoved by theA actionfof'the spring "55 towards the left in follower'engagement with said eccentric wheel. This moves the armature 80 on the arml away' from the magnet pole 18. Therefore, reven if the switch `8| is returned to "circuit closing position, the tractive forcebetween the magnet pole l8 and thearznature 80 is not sufficient because ofthe distance between the pole and the magnet: to'pull the'whee14l away from friction drive engagement with theeccen- Atric 'wheel 58. This tractive force is not suincient for that purp-oseuntil vthe eccentric wheel 58 is returned substantially into rotative position 'shown in Fig. 6 with its sideof maximumr throw in contact with the wh ee1`4|. At that instant, since the magnet l is energized, its tractive force is sufcient to attract the armature 80 and to move the wheel 4| out of contact with the eccentric wheel 58 into the inactive position shown in Fig. `6. Therefore, once the switch 8| has been opened, the complete vcircuit of the eccentric 'wheel 58 through one revolution and the rotation of the Geneva star wheel 63 one quarter revolution is assured. In the operation forchang'ing a fraineor slide, the switch 8| is rst opened to start movement of the eccentric wheel 58 and before the wheel has completed its circuit the switch is closed. The switch 8| is particularly designed to afford a time lag during switch opening operations and permit easy movement into open and closed position, 'as' willbe more fully described.

The ordinary Geneva movement 'has a locking disc curved to the same radius as the Geneva star wheel between its slots and engaging said wheel to prevent itsl rotation during the time the drive pin or tooth is out of engagement with said wheel. In the 'present construction, this locking device is shown 'in theform of a disc 85 integral with the `veccentric wheel 5B and concentric with the shaft 6D of said eccentric wheel. The Geneva star wheel 5 3 between its points has circularly concave edges86 and the locking disc 85 is circular except for a segmental cut-out 8l which is 'movable into position opposite the star wheel to release said star wheel forrotation during the drive engagement of the drive pin 65 therewith.

v -In the transitionalr periods just before the drive pin 65 nieves Vinto engagement with the star wheel 6 3 and just after thedrive pin moves out 'of engagement'with the StarwheeLthe star wheel is released from locking engagement with the locking disc 35, as shown in 8. During these intervals, the star wheel'may be accidentally displaced outof proper rotative relationship with respect'to 'the eccentric drive wheel 58. The slide on'view may thereby be displaced out of projectionf registry and there-engagement of the drive pin'65 withthestar wheel 63`Inay be blocked in the 'next'slide changing cycle. To assure against sucncondition's, thereis provided a latch device automatically 'operable to lock'the star wheel B3 at one end to a frame piece 9| secured to the casing |'l and carrying at its other free end a locking pin 92 ladapted tosnap into any one of four holes'93 quadrantly arranged on the star wheel63 between its points to'lock thereby said wheel against rotation as the hole moves into registry with saidV pin. For releasing the star wheel 53 for rotation, the eccentric wheel 58 carries a cam pinf94 adapted to ride along a wear plate '95 on the inner side of the spring bar 98 duringcertain periods of the cycle'when the drive pin 55 is `fmfoving into engagement with the star wheel63. This cam pin 94 has a rounded or cam conformation'at its end to move by this action the free end of the spring bar 90 away from the star wheel 53 against its inherent resiliency. This causes the locking pin 92 on the spring bar 90 to ybe moved out of the hole 93 in the star wheel 53 and the star wheel to bereleased for rotation.

By means of the plate 95, the cam pin'94 is able to clear the spring bar 90 while said pin is travelling on the side of its orbit diametrically opposite said plate. 'I'hisplate 95 is desirably provided with short bevels at its ends to facilitate riding action of the campin 94 on and off said plate without delaying releasing and locking action of the locking pin 92.

The cam pin '9d is located on the eccentric wheel 58 in position to effect the release of Vthe locking pin 92 out of the hole 93 just after the drive pin has entereda slot 6B in the star wheel 53 to an extent sufficient to interlock the star wheel and the drive pin. The location of the cam pin 94 is also such as release the spring har 95 a little before a'hole 93 in the star wheel 63 comes into register with the locking pin 92 and just lbefore the drive pin 65 leaves a slot B4. For that purpose, the locking pin 92 is in the radial line of the drive pin 65. Just as soon as the hole 93 reaches registered position with respect to the locking pin 92, this `pin snaps into the hole and locks the star wheel G3 against further rotation.

The plate 95 on whichthe cam pin 94 rides may be foreshortened at one end as shown or may be so bevelled at this end to permit the free end of the spring bar to move towards the star wheel 69 even before the star wheel has completed its cycle. Under these conditions, the locking pin 92 which has been moved out of one hole 93 will yieldably bear with slight pressure against the face of the kstar wheel 63 without interfering with the completion of its cycle until the next hole 93 cernes 'into'registry with said lockingpin. At that instant, the locking pin 92 snaps into the latter hola'as shown in Fig 8.

The latch device'des'cribed is more accurate and positive in its operations atthe beginning and' end of each rotative cycle of the star wheel 63 than is the locking disc 85 vand can be errployed to supplement the locking action of said locking disc, as shown, v'or ifdesired the locking disc may be dispensed'with and the latchvdevice depended on entirely toeiectrthe locking'and release of the star wheel 63'at the proper times inthe cycle.

The switch 8| is vconstructed to assure the opening of the circuit of the magnet 'l5 for a period long enough to rotate the eccentric wheel 58 into position to move'thej armature 80 a suflicient distance away from the'pole 18, so that when the closing of the circuit is reestablished, the power of the magnet will not be sucient to attract the armature. The switch 8| so designed assures the complete revolution of the eccentric Wheel 58 before coming to rest. Towards that end, the switch 8| shown in Figs. 9 and 10 comprises a pair of contacts (not shown) in the magnet circuit enclosed in a housing and normally closed by a spring (not shown). A springpressed plunger or button |02 for separating the contacts into circuit opening position upon depression thereof projects from the housing |00. For depressing the plunger |02 into circuit opening position, there is provided a lever |03 mounted on a pivot pin |08 which is secured to a frame post |05 and which supports the lever for rotation thereabout. One end of this lever |03 presents a long cam surface |06 adapted to ride over the plunger |02 and depress said plunger into circuit opening position. The other end of the lever |83 carries a handle |01. A spring |08 is connected at one end to the handle Y |07 and at the other end to a fixedV anchor ||0 and is arranged to snap into either side of the Vpivot pin |04 into inactive positions in which the circuit is closed. These extreme positions are determined by a stop bar connected to the frame structure of the switch and adapted to engage the lever |03 in either position.

The switch 8| may be enclo-sed in a casing I3 as shown in Fig. 3, with the handle i0? extending through an elongated slot Hd in the casing.

In the operation of the slide lm changer, the switch 0| is on one of its circuit closing positions shown in Fig. 10, so that the magnet 'I5 is energized and the parts of the changer are in the inactive position show-n in Fig. 6. When the operator desires to change the nlm frame or slide, he moves the lever |03 from one extreme position to its other. During this operation, the lever |03 cams the plunger |02 inwardly against the action of its spring (not shown) and opens the magnet circuit for a short interval of time.

This operation releases the iioating wheel 4| and permits it to be moved by the action of the spring 55 towards the left into driving contact with the eccentric wheel 58. The eccentric wheel 53 thereby starts rotating counterclockwise.

The circuit of thermagnet remains open just as long as 'the cam-surface |06 on the lever |03 is riding over the plunger |02. Since this cam surface |06 is of substantial length, the opening of the magnet circuit is assured for a period long enough to cause the eccentric wheel 58 to rotate counterclockwise from the normal inactive position in Fig. V6 an angular distance suiiicient to move Wheel `5| and linkage 05, 48 to the left enough to render the magnet l5 ineiective because' of the distance of the armature 80 from the magnet pole |8,.even if the circuitY of said magnet should be closed again. Therefore, after the lever |03 has moved beyond the circuit opening position described and has snapped into extreme position in which theplunger |02 is released again and the switch 8| is closed, the eccentric wheel 58 will nevertheless continue to rotate counterclockwise to rotate the star wheel 63 one quarter revolution, and until said eccentric wheel substantially reaches the rotative position shown in Fig. 6. At this time, thearmature 30 will be suciently close to the magnet pole '1,3 to be attracted thereby. This addition moves the floating wheel 4| out of dfive` contact with the eccentric wheel 58 and wheel 4| wiil remain in Y this inoperative position until the lever |03 in the switch 8| is swung into the opposite extreme position by the operator when he desires a change of views.

It is desirable for the eccentric Wheel 58 to stop approximately in the position shown in Fig. 6 at the end of each slide changing operation. After the eccentric wheel 58 has moved beyond the position shown in Fig. 8 where it is free from the restraining influence of the star wheel 63, it has a tendency to race and unless it is retarded it may overrun its desired stopping position shown in Fig. 6. For that reason, the spring bar is arranged to apply a braking action to the eccentric wheel 58 through the plate 95 secured thereto. This plate bears against the locking disc 85 through the inherent resiliency of the spring bar 90. The force with which this plate 95 bearsagainst the locking disc 85 may be adjusted by adjustment of the anchored end of the spring bar 00 through an adjusting screw at this end, or if desired, a washer may be employed in connection with the screw securing said spring bar 30 to the frame piece 0| to adjust the braking pressure on the locking disc.

It should be noted that the slide film changer of the present invention is in the form of a compact self-contained unit separate from the projector and is easily attachable thereto and easily y removable therefrom as a unit.

VWhile the invention has been described with particular reference to a specific embodiment, it is to be understood that it is not to be limited thereto but solely by the scope of the appended claims.

What is claimed is l. In a slide changer, a Geneva movement for operating a film feed shaft step by step and comprising a star wheel, a drive wheel having a drive tooth for said star wheel, latch means for locking said star wheel automatically against rotation when said tooth moves out of drive engagement with said star wheel and including a relatively thin wide elongated spring bar Xed at one end to a iixed part of said slide changer and urged towards said star wheel at its other end by its inherent resiliency, and a pin and hole connection between the free end. of said bar and said star wheel to lock said star wheel, a part of said bar being disposed adjacent said drive wheel and having an engagement surface thereon, and a cam pin on said drive wheel disposed so as to engage said engagement surface for camining the free end of said bar away from said star wheel substantially as said tooth moves into drive engagement with said star wheel to release said star wheel for rotation under the control of said tooth.

2. In a slide changer, a Geneva movement for operating a film feed shaft step by step, a motordriven wheel for driving said Geneva movement, a magnet, an armature mounted in position to be attracted by said magnet when said armature is within a predetermined distance from the pole of said magnet, a iioating mount for said drive wheel permitting said drive wheel to be moved towards and away from drive engagement with said Geneva movement, means connecting said armature and said drive wheel in relationship to cause said armature to move away from said magnet pole as said drive wheel moves towards drive engagement with said Geneva movement and to hold said drive wheel out of drive engagement with said Geneva movement while said magnet is attracting saidgarmature, means for moving said armature away from said pole beyond atns iorcontroliinejthe'circnitcilsaidlmaa et teY nait, slide changes. andl comprising means.

fo normailyjmaintaining said. circuit clcsedand manually'movable means onerablejby a'sinsle.

ti.. longthoi timevv and tojthenv clodofsaid circuit, re the switchv means comprises' contacts normally closed, by spring action', alnlungei' de-v nressible tov separate saidcontacts and a. plunger denressor having. yajcani surface of, substantial length adapted. to. be manipulatedinto. engage:

:gestaan said pioneer to depress said plunger.' as aid depressor is'movedfrom one positionA to another.

3. In. a slide changer, a Geneva. movement f cr operating a nlmrfeedshdfistep by step, a motordriven wheel for driving. said Geneva movement, arnagnet, an armature mounted in "position to be. 'attracted by said magneti. when., saldi annat'ure is within aV predetermined distance from the 'noie orV said magnet, a Heating, mount for said,y drivewheel permitting said,` drive wheel tov b vedtowards `and awayl from drive engage; with said Geneva'movement, means 'con-.- Ang said armature and saidl drivel wheel in relationship to cause said armature to nieve avvay from said magnet pole as saidjdrive wheel moves tQWallds. drive engagement with s aid Geneva.

movement and to holdjsaid drivev wheel outV of drive engagement: with said Geneva movement. while said magnet is attracting, said4 armature, in ns for vmoving said armature fdvi/,ay from said p beyond attracting, distance.y and then back towards said polel within attracting distance as said drive wheel is operating'said Geneva movement, and switch meansk for controlling `the circuit' of said magnet to perm-it' slide changes and comprising means for'normally maintaining said circuitl closed and manually movable means operable by a single manipulation to Opensaid circuit for a substantial length of time and to then close said circuit, said manually movable means comprising a plunger depressible to. separate said contacts and a plunger depressor having 'a cam surface of substantial length thereon adapted to be, manipulated into engagement with said plunger as said depressor is moved from one in'- a-ctive position. te another, said switch means comprising spring meansforsnapping vsaid depressor into either one of. two inactive positions in which the plunger is released.

ri. In a slide lm changer, a Geneva movement for operating alm feed shaft step by step and comprising a star wheel, a drive wheel having a drive tooth for engaging said star wheel, latch means for locking said star Wheel automatically against rotation when said tooth moves out of drive engagement with said star Wheel and ncluding an elongated thin Wide bar having one end secured to a xed part of said changer and having its opposite end free for resilient movement towards and away from a side of said star wheel and urged towards said star Wheel, land a pin and hole connection between said bar and said side of said star wheel to lock said star wheel, cam means carried by a side of said drive wheel for ca-mming said bar into position to interrupt said pin and hole connection automatically when said tooth moves into drive engagement with said star wheel, said drive wheel being eccentrically mounted for rotation, a motor-driven wheel movable into operative engagement with attrae 'ngldistancejasslaid drivewneelis o.' rating said'v Geneva movement. and

Pilletcn. te Open said circuit-ier a' snbstan# d. veT 'engagement with said star Wheel and lncl.

having] itscnncsite'end free for resilient nievemerrt; towardsvand away from a Side ofsaid star Wheel. and 'ureedtcvvards said star vvlieel, and a nin and liniel connection between said bar and said side ci said. star wheel to locls saidstar Wheel7 a. lockinsydisc carried by said drive Wheel and successively closely dttins recessed portions ci said star wheel. after each'step.. by stepV operation thereof," cam" means carried by a sidey ofsaid drive.r wheel for camming said bar into position tol' interrupt saidpin and hole connection automatically when said tooth moves into drive engagementlwithY said star wheel, said drive Wheel being eccentrically mounted for rotation, a motordriven wheel movable: into operative engagement with said Adrive wheel, the eccentricity of said drive wheel being eiective Vduring rotation thereoftek move' saidmotor-driven wheel into a nondrivingfposition each time said star Wheel comnietes 4one 'forward step icr advancing film, and release holding ineanslfor homing said motordrivenwheelin said non-.driving position.

'6, a slide lm' changer, a Geneva movement fonoperating a lm'feed shaftl step by step, a continuouslyrotating electric motor driven wheel, for driving said Geneva movement, energized electron-magnet means for normally maintaining said wheel out of drive engagement with said Geneva movement, a circuit for supplying current to ,Said electro-magnet means, spring means constantly urging said wheel toward drive en-V gagement with'said Geneva movement, switch means forcontrolling the'current to said electromagnet. means to permit slide changes, said switch means comprising contact means for normally maintaining said circuit4 closed, a plunger for opening said contacts, and manually movabile I neansy having camming engagement with saidV plunger and opening said circuit for a sub-l stantial length of time so as to allow said spring means to move said wheel out of the holding influence of said electro-magnet means and to then close said circuit, and means on said Geneva movement for returning said wheel t0 its nondriving position after each slide changing operation.

7. In a slide lm changer, a Geneva movement for operating a film feed sha-ft step by step including a star wheel and a toothed wheel for driving said star wheel, continuously rotating electric motor driven means for driving said toothed wheel, means for interrupting the drive from said motor driven means to said toothed wheel, brake means having a part rotatable with said toothed Wheel and a non-rotatable part positioned adjacent the toothed wheel, said parts being normally disengaged from each other but movable into mutual engagement after the toothed wheel starts to rotate for retarding the efiective during rotation. thereof an. elongatedl tninvvide bar having 0.11 end secured.` te. a lined. Part. of: Said cleanser and.

l' rotation of said toothed wheel after it has rotated out of drive relation with respect to said star wheel and is free from said electric motor driven means. Y

8. In a slide lm changer, a Geneva movementI for operating a film feed shaft step by step including a star Wheel and a toothed wheel for driving said star wheel, continuously rotating electric motor driven means for driving said toothed Wheel, latch means for locking said star wheel against rotation automatically when said star wheel is free from drive control of said toothed wheel, means for interrupting the drive from said electric motor driven means to said toothed wheel by disengaging the former from said toothed wheel, and brake means carried by said latch means having a part rotatable With said toothed wheel and a non-rotatable part positioned adjacent the toothed Wheel, said parts being normally disengaged from each other but mov-able into mutual engagement after the toothed wheel starts to rotate for retarding the rotation of said toothed wheel after it has rotated out of drive relation with respect to said star wheel and as said electric motor driven means is being disengaged therefrom.

9. In a slide changer, a Geneva movement for operating a lm feed shaft step by step and comprising a star wheel, a drive Wheel having a drive tooth for actuating said star wheel, continuously rotatable electric motor driven means for driving said drive wheel, means for disengaging and interrupting the drive from said electric motor driven means to said drive wheel, latch means for locking said star Wheel automatically against rotation substantially as said drive tooth moves out of drive engagement with said star wheel, said locking means including an elongated bar xedly mounted adjacent one end thereof to a fixed part of said changer and having its opposite end free and arranged for resilient movement towards said star wheel, a pin and hole connection between the free end portion of said bar and said star wheel to lock said star Wheel against rotation, and a braking member carried by an intermediate portion of said bar and normally out of engagement with said drive Wheel but pressing against said drive Wheel with spring action to retard the rotation of said drive Wheel after it has rotated out of drive relation with respect to said star wheel and while said electric motor driven means is disengaged.

10. A slide lm changer for attachment to the.

lm feed shaft of a'slide lm projector, said slide film changer comprising a casing, a Geneva movement in said casing for operating said lm feed shaft step by step, a motor driven wheel for driving said Geneva movement, an electric motor `carried by said casing and operatively engaging said driven wheel, electro-magnet means in said casing for releasably holding said driven wheel out of driving engagement with said Geneva movement, said casing mounting said Geneva movement, said driven Wheel, said electric motor and said electro-magnet means in a self-contained unit adapted to be readily attached to the projector film feed shaft in operative position as a unit, said Geneva movement comprising a star Wheel within one end of said casing, means extending externally of said casing for coupling said star wheel to said film feed shaft, and a leg secured to said casing toward an opposite end thereof for supporting said unit in operative position with respect to said projector.

l1. A unitary slide film changer adapted to be readily detachably connected to a rotatable strip film feed shaft of a projector, said changer comprising aGeneva movement for operating said film feed shaft step by step, an electric motor and a motor driven Wheel for driving said Geneva movement, electro-magnet means for interrupting the transmission of power from said driven wheel to said Geneva movement, frame means mounting said Geneva movement, said motor, said driven wheel and said electro-magnet means into a self-contained unit, means adapted to detachably attach said Geneva movement to said projector feed shaft and for maintaining said slide nlm changer in operative position as a unit, and a leg having a supporting roller at its lower end, said leg being secured to said frame for supporting an end of said unit spaced from said Geneva movement in an elevated operative position With respect to the supporting circuits for said projector.

. ROBERT A. LIGHTBURN.

MERVYN W. PALMER.

vReferences Cited in the le of this patent UNITED STATES- PATENTS 

